JP2018013513A - Method for producing elastic roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an elastic roller which suppresses occurrence of air bubbles in the vicinity of ends of an elastic layer and has high durability.SOLUTION: A method for producing an elastic roller having a cylindrical body, a shaft body having ends with a smaller diameter than the cylindrical body at least one end of the cylindrical body, and an elastic layer on the outer periphery of the cylindrical body includes: a step of coating at least end surfaces of the cylindrical body with a rubber composition forming the elastic layer; a step of removing a tip side coating portion coating a tip side rather than a base end side portion coating a region of 0.5 mm or more and 5 mm or less in a tip direction of the end from the end surface in the rubber composition, releasing the sealed state, and removing the base end side coating portion; and a step of curing the rubber composition before or after removing the base end coating portion.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing an elastic roller, and more particularly to a method for manufacturing an elastic roller having high durability by suppressing the generation of bubbles in the vicinity of an end portion of an elastic layer.

  For image forming apparatuses such as printers such as laser printers and video printers, copiers, facsimiles, and composite machines of these, for example, a developing roller for carrying and conveying the developer, a developer supplying roller for supplying the developer to the developing roller, Various types of elastic rollers such as a conveyance roller for conveying the recording medium, a transfer roller for transferring the developer to the recording medium, a fixing roller for fixing the developer on the recording medium to the recording medium, and a pressure roller for pressing the fixing roller. It has.

  These elastic rollers include, for example, a shaft body and an elastic layer formed on the outer periphery thereof, and can be manufactured by cutting excess rubber after covering the outer periphery of the shaft body with rubber (for example, Patent Document 1). ~ 5). Specifically, the elastic roller is formed by integrally extruding the shaft body and the unvulcanized rubber, and then extruding the unvulcanized rubber continuously on the outer periphery of the shaft body to cut off the excess unvulcanized rubber, Manufactured by vulcanizing unvulcanized rubber.

JP 2002-66979 A JP 2006-305770 A JP 2007-212864 A JP 2011-226568 A JP 2006-123256 A

  By the way, in recent years, the diameter of the elastic roller may be increased due to a demand for energy saving, a demand for higher durability and a higher speed in the image forming apparatus. For example, since the fixing roller can retain a large amount of heat when the diameter thereof is increased, energy consumption can be reduced and the number of rotations can be suppressed, thereby meeting the above demand.

  In addition, a rod-like body or a cylindrical body having a constant outer diameter is often used as the shaft body. However, in terms of the structure of the fixing unit, small-diameter end parts (bearing parts) are formed at both ends of the central part where the elastic layer is formed. Part) may be used.

  Using such a shaft body, when an elastic roller, particularly an elastic roller having a large diameter, is manufactured by integral extrusion as described above, a phenomenon that bubbles are generated near the end of the elastic layer is newly confirmed. It was. If air bubbles are present in the vicinity of the end of the elastic layer, the elastic layer is peeled off from the shaft body due to the use of the elastic roller, and the durability is lowered. Further, due to the presence of bubbles, the physical properties such as hardness in the vicinity of the end portion of the elastic layer are different from those of other portions, and the elastic roller cannot sufficiently perform a desired function.

  An object of the present invention is to provide a method for producing a highly durable elastic roller by suppressing the generation of bubbles in the vicinity of the end of the elastic layer.

In the present invention, bubbles generated in the vicinity of the end of the elastic layer are hollow regions existing in the elastic layer, and can be distinguished from the cells of the foamed elastic layer, for example. Specifically, in the foamed elastic layer, among the hollow regions existing in the vicinity of the shaft body (for example, near the boundary between the foamed elastic layer and the shaft body), those having a diameter of 1 mm or more are determined to be bubbles and less than 1 mm. Something is determined as a cell. Here, the diameter of the hollow region can be measured using a microscope.
Cells and bubbles can also be distinguished by their appearance. Specifically, when a skin layer is formed at the boundary between the foamed elastic layer and the shaft body, the hollow region in the skin layer is determined as a bubble.

  When manufacturing the elastic roller by coating the rubber composition on the shaft body having the cylindrical main body and the end, the present inventors provide the end face of the cylindrical main body to which the end is connected and the rubber composition. The space is sealed, and the air sealed in this sealed space penetrates into the rubber composition when removing the rubber composition or between the rubber composition and the outer peripheral surface of the cylindrical body, It has been found that bubbles are generated near the end of the elastic layer. It has been found that this air sealing becomes more prominent as the elastic roller becomes larger in diameter and as the outer diameter difference between the cylindrical main body and the end of the shaft increases. Based on these findings, further investigations were made on the means for removing the sealed air. In order to discharge the sealed air without entering the rubber composition or the like, an exhaust hole (air hole) leading to the sealed space was used. ) Is not sufficient to simply provide the rubber composition, and it has been found effective to remove (cut) a part of the rubber composition in advance so as to release (release) the sealed state of the sealed space. The present invention has been made.

That is, the subject of this invention was achieved by the following means.
(1) A method of manufacturing an elastic roller having a cylindrical main body, a shaft body having an end portion having a diameter smaller than that of the cylindrical main body at at least one end portion of the cylindrical main body, and an elastic layer on the outer periphery of the cylindrical main body. There,
A step of covering at least an end surface of the cylindrical main body in a sealed state with a rubber composition forming the elastic layer;
The rubber composition is sealed by removing a distal end side covering portion covering a distal end side from a proximal end covering portion covering an area of 0.5 mm or more and 5 mm or less from the end face toward the distal end of the end portion. Releasing the state and then removing the proximal covering portion;
And a step of curing the rubber composition before or after removing the base end side covering portion.
(2) The covering step is the method for manufacturing an elastic roller according to (1), wherein the whole shaft body is covered.
(3) The removing step is the elastic roller manufacturing method according to (1) or (2), in which the base end side covering portion and the tip end side covering portion are each removed once or a plurality of times.
(4) The covering step is the method for manufacturing an elastic roller according to any one of (1) to (3), in which the rubber composition and the plurality of shaft bodies are continuously extruded.
(5) The step of covering the elastic roller according to any one of (1) to (4), wherein a thickness of the rubber composition covering an outer periphery of the cylindrical main body is 1 mm or more and 20 mm or less. Production method.
(6) The method according to any one of (1) to (5), wherein the shaft body has an outer diameter difference between the cylindrical main body and the end portion of more than 0 mm and 15 mm or less.
(7) The elastic roller manufacturing method according to any one of (1) to (6), wherein the elastic roller has an outer diameter of 20 mm to 60 mm.

In the present invention, the end surface of the cylindrical main body means a surface to which end portions are connected and connected. Further, the base end of the end portion means an end portion connected to the end face of the cylindrical main body, and the tip end means an end portion opposite to the base end, that is, a free end of the end portion.
In the present invention, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

  According to the present invention, it is possible to manufacture a highly durable elastic roller by suppressing the generation of bubbles in the vicinity of the end of the elastic layer.

FIG. 1 is a schematic perspective view showing an elastic roller manufactured by the manufacturing method of the present invention. FIG. 2 is an explanatory cross-sectional view illustrating a removing step in the manufacturing method of the present invention. FIG. 3 is a schematic view showing a durability test apparatus used for carrying out the durability test of the elastic roller in the embodiment.

First, the elastic roller manufactured with the manufacturing method of this invention is demonstrated.
The elastic roller of this invention should just have a shaft body and an elastic layer, and another structure is not specifically limited. For example, a coat layer or a surface layer may be provided on the outer periphery of the elastic layer, and an adhesive layer or a primer layer may be provided between the shaft body and the elastic layer or between the layers.

The shape and dimensions of the elastic roller are not particularly limited, and are appropriately set according to the application, function, image forming apparatus, and the like. For example, the shape that can be taken by the elastic roller includes a so-called straight shape, crown shape, reverse crown shape, and the like.
The outer diameter of the elastic roller is usually about 20 to 30 mm when used in an image forming apparatus, but is 30 to 60 mm, for example, when the diameter is increased to meet recent demands. Therefore, in the present invention that can increase the diameter, the outer diameter of the elastic roller can be 20 to 60 mm. The axial length is usually set to a length that conforms to A3 size or A4 size (both refer to Japanese Industrial Standards).

  The elastic layer may be a foamed elastic layer or an unfoamed (solid) elastic layer, and is appropriately selected depending on the application and characteristics. When an elastic roller is used as the fixing roller of the image forming apparatus as the elastic layer, a foamed elastic layer is preferably selected.

  As shown in FIG. 1, an elastic roller 1 as an example of the elastic roller of the present invention includes a shaft body 2 and a foamed elastic layer 3 formed on the outer peripheral surface thereof.

As shown in FIG. 1, the shaft body 2 includes a cylindrical main body 2A and end portions 2B connected to both end surfaces 2C of the cylindrical main body 2A.
The cylindrical main body 2A is a portion where the foamed elastic layer 3 is formed, and has a uniform outer diameter in the axial direction. The end 2B is uniform in the axial direction and has an outer diameter smaller than that of the cylindrical main body 2A. The shapes of the cylindrical main body 2A and the end 2B are not particularly limited, and examples thereof include a cylindrical shape or a columnar shape (bar shape).
The dimensions of the cylindrical main body 2A and the end 2B are set as appropriate according to the application and the like. In the shaft body 2, the outer diameter difference between the cylindrical main body 2A and the shaft body 2B is preferably more than 0 mm and not more than 15 mm, more preferably 1 to 15 mm, and particularly preferably 1 to 10 mm. . When the difference in outer diameter is within the above range, air hardly remains between the cylindrical main body 2A and the small-diameter end 2B, and generation of bubbles in the vicinity of the end of the elastic layer can be suppressed.

  The shaft body 2 only needs to have good conductive properties, and is usually made of iron, aluminum, stainless steel, brass, or the like. Further, the shaft body 2 may be a shaft body that is made conductive by plating an insulating core body such as a thermoplastic resin or a thermosetting resin. Furthermore, the shaft body 2 may be a thermoplastic resin or a thermosetting resin. The shaft body may be formed of a conductive resin in which carbon black or metal powder is blended as a conductivity imparting agent.

The foamed elastic layer 3 is basically the same as the foamed elastic layer in a conventionally known elastic roller for an image forming apparatus, and is formed on the outer peripheral surface of the cylindrical main body 2A.
The foamed elastic layer 3 has a so-called “sponge-like” shape having cells (not shown in FIG. 1) inside and / or on the outer surface thereof. Here, the cell refers to a hollow region opened in or on the surface of the foamed elastic layer 3 caused by foaming or decomposition of a foaming agent contained in the foamed rubber composition described later, and is different from bubbles as described above.

  Although the thickness of the foaming elastic layer 3 is not specifically limited, For example, it is 2-42 mm, Preferably it is 4-30 mm, More preferably, it is 4-20 mm.

The foamed elastic layer 3 has the following characteristics.
That is, the hardness is preferably 15 to 60, and more preferably 20 to 50. Thereby, the effect of ensuring the nip width and improving the printing characteristics can be obtained. The hardness can be measured using a hardness meter Asker C constant pressure loader.

  Moreover, it is preferable that a cell diameter is 100-400 micrometers, and it is more preferable that it is 150-350 micrometers. Thereby, the effect of improved printing is obtained. The cell diameter can be measured by layer analysis using a microscope VH-5000.

  An elastic roller manufacturing method of the present invention (also referred to as a manufacturing method of the present invention) includes a cylindrical main body, a shaft body having an end having a smaller diameter than the cylindrical main body at least at one end of the cylindrical main body, and the cylindrical main body. Is a method of manufacturing an elastic roller having an elastic layer on the outer periphery of the roller. For example, the elastic roller 1 can be suitably manufactured.

  The production method of the present invention includes a step of covering at least an end surface of a cylindrical main body with a rubber composition forming an elastic layer in a hermetically sealed state, and a region from 0.5 to 5 mm from the end surface to the tip direction of the rubber composition. Removing the distal-side coating portion covering the distal end side from the proximal-side coating portion coating the base, releasing the sealed state, and then removing the proximal-side coating portion, and before removing the proximal-side coating portion Or a step of curing the rubber composition later.

  The manufacturing method of the present invention will be specifically described by taking as an example the case where the shaft body 2 is used as a shaft body having an end portion having a smaller diameter than the cylindrical body at at least one end portion of the cylindrical body. To do.

  In the manufacturing method of the present invention, first, the shaft body 2 is prepared. The two shaft bodies are as described above, and are formed of the above-described materials. The shaft body 2 is preliminarily coated with an adhesive or primer on the outer peripheral surface of the cylindrical main body by a spray method, a dipping method, or the like as necessary, and an adhesive layer or primer layer is formed on the outer peripheral surface. Is good.

  On the other hand, a rubber composition for forming an elastic layer is prepared or prepared. The rubber composition to be prepared or prepared is selected according to the elastic layer. For example, when the foamed elastic layer 3 is formed, a foamed rubber composition is selected, and when a solid elastic layer is formed, a non-foamable (unfoamed) rubber composition is selected. For example, the rubber composition includes a rubber and a conductivity-imparting agent, and may optionally include a foaming agent and / or various additives.

  The foamed rubber composition used when forming the foamed elastic layer 3 may be a composition containing rubber, a foaming agent, and various additives as required, for example, a foamed silicone rubber composition, particularly An addition reaction type foamed silicone rubber composition is preferred. As an addition reaction type foamed silicone rubber composition, it contains a vinyl group-containing silicone raw rubber, a silica-based filler, a foaming agent, an addition reaction crosslinking agent, an addition reaction catalyst, a reaction control agent, and a conductivity imparting agent. If desired, an addition reaction type foamed silicone rubber composition containing an organic peroxide crosslinking agent and various additives may be mentioned. As these components, for example, “addition reaction type foamed silicone rubber composition” described in JP-A-2008-076751 can be used, and the contents described therein are incorporated in the present specification.

  The rubber composition preferably has a rubber plasticity (measurement temperature 23 ° C.) in an unvulcanized state of 150 to 300, more preferably 200 to 250. When the rubber plasticity is within the above range, the surface of the unvulcanized rubber dispensed during extrusion molding becomes smooth, and the dispensed outer diameter can be managed. The rubber plasticity is measured by a plasticity meter. Specifically, 2 g of unvulcanized rubber is weighed and set on a plasticity meter, and a load is applied. Read the value 3 minutes after applying 9.8N load.

In the production method of the present invention, at least the outer periphery of the cylindrical main body 2A of the shaft body 2 and the end surface 2C are covered with a rubber composition in a sealed state.
The means for coating with the rubber composition may be any means, but is preferably extrusion (dispensing). Extrusion molding can be performed using a straight head extruder or a cross head extruder. The extrusion may be formed by intermittently feeding shafts one by one, or may be formed continuously by arranging a plurality of shafts in the axial direction. In view of productivity, it is preferable to continuously perform extrusion.

  Although the temperature at the time of extruding a rubber composition is not specifically limited, It is preferable that the temperature of a rubber composition is 10-30 degreeC, and it is more preferable that it is 15-25 degreeC. When the extrusion temperature is within the above range, the progress of vulcanization is suppressed, and an effect that the extrusion can be stably performed for a long time is obtained.

  As the thickness of the rubber composition 6 covering the outer periphery of the cylindrical main body 2A, the thickness of the rubber composition 6 molded on the cylindrical main body 2A is preferably 1 to 20 mm, more preferably 3 to 15 mm, More preferably, it is set to 3 to 9 mm. When the thickness of the rubber composition 6 is in the above range, the heat conduction is well balanced and a uniform elastic layer can be obtained. In addition, the thickness of the rubber composition 6 molded on the tip side from the end surface 2C of the cylindrical main body 2A is not particularly limited as long as the end surface 2C can be sealed, but is preferably 2 to 15 mm, for example.

  When the rubber composition 6 is coated on the outer periphery of the shaft body 2, preferably by extrusion molding, the entire shaft body 2 is coated with the rubber composition 6, particularly when extrusion molding is continuously performed. Specifically, as shown in FIG. 2, the rubber composition 6 is in contact with the outer periphery of the cylindrical main body 2A and gradually becomes smaller in diameter when the end surface 2C of the cylindrical main body 2A is exceeded. Is formed into a tubular shape that touches the outer periphery of the tube. An internal space 5 closed by the rubber composition 6 formed into a tubular shape, the end surface 2C of the cylindrical body 2A, and the outer peripheral surface of the shaft body 2B is formed, and at least the end surface 2C of the cylindrical body 2A is in a sealed state. At this time, the internal space 5 is filled with gas, usually air, present in the environment in which this step is performed. In the case of extrusion molding, air sealing is considered to occur due to a decrease in the extrusion pressure of the rubber composition 6.

Next, in the manufacturing method of the present invention, a step of removing an excess rubber composition formed on the tip side of the end surface 2C of the cylindrical main body 2A is performed. This removing step is performed in at least two stages.
In this step, the surplus portion disposed outside the cylindrical main body 2A in the molded rubber composition 6 is divided into at least two of a proximal end side covering portion 6a and a distal end side covering portion 6b. That is, the base end side covering portion 6a is a portion that covers a region from 0.5 to 5 mm in the distal direction from the end surface 2C of the cylindrical main body 2A, and the tip end side covering portion 6b is more than the base end side covering portion 6a. The part covering the tip side. In addition, in FIG. 2, the base end side coating | coated part 6a was shown with the broken line.

  In the production method of the present invention, the boundary between the base end side covering portion 6a and the tip end covering portion 6b, that is, the cutting position of the rubber composition for removing the tip end covering portion 6b is from the end surface 2C of the cylindrical main body 2A. It is 0.5 mm or more and 5 mm or less in the distal direction. If the cutting position is less than 0.5 mm, the generation of bubbles in the vicinity of the end of the elastic layer can be suppressed. However, since the cutting margin is small (the rubber escapes), the standard size of the rubber position may be off. is there. On the other hand, when the cutting position exceeds 5 mm, there is sufficient cutting margin, so that it can be cut to the standard size of the rubber position, but the generation of bubbles near the end of the elastic layer may not be suppressed. The cutting position is preferably 2 to 4 mm from the viewpoint that both the prevention of bubbles and the cutting of the rubber position to the standard size can be achieved.

  Here, in the state of being covered with the rubber composition 6, the position of the end surface 2C of the cylindrical main body 2A can be confirmed by the setting of the cutting machine.

  The cutting position is related to the outer diameter difference of the shaft body 2. Specifically, when the difference in outer diameter is more than 0 mm and 15 mm or less, the cutting position is preferably 2 to 4 mm. If the cutting position is set in the above range using the shaft body 2 having the outer diameter difference in the above range, the effect of the present invention becomes remarkable.

  In the removing step, first, the distal end side covering portion 6b is removed (first step). Specifically, the distal end side covering portion 6b is removed together with the proximal end side covering portion 6a located on the distal end side with respect to the cutting position set in the proximal end side covering portion 6a. By this first step, the front end side covering portion 6b is removed, and the sealed state of the end surface 2C is released. If it does so, the rubber composition 6 shape | molded by the pipe will become a truncated cone shape which the edge part opened. Thereby, the internal space 5 sealed with the rubber composition 6 is opened, the air sealed in the internal space 5 is discharged, and the inside of the internal space 5 becomes almost normal pressure.

  In the removing step, the rubber composition remaining in the first step is then removed from the surplus rubber composition (second step). In the second step, the rubber composition, usually the (residual) base end side covering portion 6a, and the like are removed so that both end faces of the rubber composition and the cylindrical main body 2A are substantially flush with each other.

In the removing step, the base end side covering portion 6a and the tip end side covering portion 6b can be removed once or a plurality of times, respectively.
The method for removing the rubber composition 6 is not particularly limited, and examples thereof include manual cutting and automatic cutting. In particular, the second step is not stable in the state in which the excessive rubber composition 6 to be removed protrudes in a truncated cone shape (ring shape) from the end surface 2C of the cylindrical main body 2A. An automatic cutting method in which cutting with a sharp blade is performed is preferable.

  When the removal process of the surplus rubber composition is performed in this manner, the air sealed in the internal space 5 is discharged to the outside, and the rubber composition and the outer peripheral surface of the cylindrical main body 2A are also contained in the rubber composition. It is possible to prevent the gas sealed in the internal space 5 from entering between.

In the production method of the present invention, the step of curing the rubber composition 6 is performed before or after the proximal end side covering portion 6a is removed (second step). In the present invention, it is preferably performed after the second step.
Although the process to harden | cure is not specifically limited, Usually, the method of carrying out primary vulcanization | cure of a rubber composition and then secondary vulcanization | cure is mentioned suitably.

  The primary vulcanization of the rubber composition may be performed under conditions sufficient for a rubber contained in the rubber composition, for example, a vinyl group-containing silicone raw rubber to crosslink and the foaming agent to decompose or foam. For example, the rubber composition is usually heated to about 170 to 500 ° C., particularly 200 to 400 ° C. by a heating furnace such as an infrared heating furnace or a hot air oven, a heating machine such as a dryer, and the like. In particular, it is heated for 5 to 30 minutes.

  The secondary vulcanization of the rubber composition is a step of more reliably crosslinking the rubber composition crosslinked by the primary vulcanization, and the physical properties of the cured product obtained by curing the rubber composition are stabilized by the secondary vulcanization. The effect of doing is obtained. In the secondary vulcanization, for example, the rubber composition after the primary vulcanization is further extruded, and is, for example, 180 to 250 ° C., preferably 190 to 230 ° C., preferably 1 to 24 hours, Is heated again using a mold, for example, at 130 to 200 ° C., preferably 150 to 180 ° C., for 5 minutes to 24 hours, preferably 10 minutes to 10 hours. Is done.

  In this way, an elastic layer is formed.

  In the manufacturing method of this invention, the process of adjusting the shape or outer diameter of a primary hardening body or a secondary hardening body (elastic layer) can be implemented if desired. In this step, for example, each process such as a polishing process, a cutting process, a blasting process, and a turning process can be appropriately selected.

  In the production method of the present invention, if desired, other layers such as a surface layer and a coat layer can be formed on the outer peripheral surface of the elastic layer. The other layer is formed by, for example, applying an appropriate composition such as a resin composition or a rubber composition to the outer peripheral surface of the elastic layer and then curing.

According to the production method of the present invention having the above steps, since the sealed gas can be discharged when the rubber composition is coated, the rubber composition is removed when the rubber composition is removed, and the rubber composition and the cylindrical body. Gas can be prevented from entering between the outer peripheral surface of 2A. Accordingly, it is possible to suppress the generation of bubbles in the vicinity of the end portion of the elastic layer and to manufacture a highly durable elastic roller.
As described above, the manufacturing method of the present invention capable of preventing the intrusion of gas is an elastic roller having a shaft body 2 having a large outer diameter difference between the cylindrical main body 2A and the end 2B as a method of manufacturing a large-diameter elastic roller. It is suitable as a method for producing 1.

Example 1
A shaft body (manufactured by SUM22) 2 having the following dimensions was prepared, which was composed of a cylindrical main body 2A having end portions 2B connected to both end faces 2C.
Dimensions of cylindrical main body 2A: outer diameter 18 mm, axial length 312 mm
Dimensions of end 2B: outer diameter 9 mm, axial length 8.5 mm
Difference in outer diameter between cylindrical main body 2A and end 2B: 9 mm
Next, the shaft body 2 was washed with ethanol, and a silicone primer (trade name “Primer No. 16”, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to the surface of the cylindrical main body 2A. The primer-treated shaft body 2 was fired at a temperature of 150 ° C. for 10 minutes using a gear oven, and then cooled at room temperature for 30 minutes or more to form a primer layer on the surface of the cylindrical main body 2A.

  Next, 100 parts by mass of a silicone rubber composition “KE-904FU” (manufactured by Shin-Etsu Chemical Co., Ltd .: trade name) containing a vinyl raw silicone rubber and a silica-based filler, and an addition reaction crosslinking agent “C-153A” (Shin-Etsu) Chemical Industry Co., Ltd .: trade name) 2.0 parts by mass, organic foaming agent azobis-isobutyronitrile “KEP-13” (Shin-Etsu Chemical Co., Ltd .: trade name) 2.5 parts by mass, and addition reaction catalyst An appropriate amount of platinum catalyst, 0.5 parts by mass of a reaction control agent “R-153A” (manufactured by Shin-Etsu Chemical Co., Ltd .: trade name), and an organic peroxide crosslinking agent “C-3” (manufactured by Shin-Etsu Chemical Co., Ltd .: (Product name) An appropriate amount and 1.0 part by mass of a heat resistance improver “KEP-12” (manufactured by Shin-Etsu Chemical Co., Ltd .: product name) are sufficiently kneaded with two rolls, and an addition reaction type foamed silicone rubber composition A product was prepared. The rubber plasticity of this addition reaction type foamed silicone rubber composition was 210.

  The addition reaction type foamed silicone rubber composition was integrally dispensed together with the shaft 2 using an extrusion molding machine equipped with a crosshead die. Specifically, at a temperature of about 20 ° C., the addition reaction type foamed silicone rubber composition is dispensed so that the entire cylindrical main body 2A and the cylindrical end 2B are covered to a thickness of 5 mm or 20 mm. did. Thereby, the end surface 2C of the cylindrical main body 2A was covered with the addition reaction type foamed silicone rubber composition in a sealed state (covering step). The internal space 5 was formed up to 5 mm on the tip side from the end surface.

  Subsequently, the process of removing a rubber composition was performed. More specifically, the shaft body 2 coated with the addition reaction type foamed silicone rubber composition is set on a general-purpose lathe, and the tip side is covered with respect to a position 3.5 mm from the end surface 2C of the cylindrical main body 2A. The distal end side coating portion 6b of the foamed silicone rubber composition was excised together with the proximal end side coating portion 6a of more than 3.5 mm and up to 5.0 mm (the sealed state of the end surface 2C was released). Subsequently, the base end side covering portion 6a (remaining portion) of the addition reaction type foamed silicone rubber composition covering the end surface 2C to a position of 3.5 mm was cut in the same manner.

Next, using an infrared heating furnace (IR furnace), the addition reaction type foamed silicone rubber composition covering the cylindrical main body 2A was primarily vulcanized at 250 ° C. for 10 minutes. Then, further using a gear oven, secondary vulcanization was carried out at 200 ° C. for 7 hours and left at room temperature for 1 hour (step of curing the rubber composition).
In this way, two types of elastic rollers having outer diameters of 28 mm and 58 mm were manufactured.

(Examples 2 to 5)
In Example 1, the cutting position for cutting the distal end side covering portion 6b was changed from 3.5 mm to 3 mm, 4 mm, 2 mm, or 2.5 mm, respectively. 5 elastic rollers (2 types) were produced.

(Example 6)
In Example 1, the elastic roller of Example 6 (2 types) is the same as Example 1 except that the outer diameter of the cylindrical main body 2A is changed to 12 mm (outer diameter difference from the end 2B: 3 mm). Manufactured.

(Comparative Example 1)
In Example 1, the cutting position was changed to 5 mm, and a through hole was made with a needle having an outer diameter of 0.6 mm from the cut surface of the addition reaction type foamed silicone rubber composition to the end of the cylindrical main body 2A. The elastic roller of Comparative Example 1 was produced basically in the same manner as in Example 1.

(Comparative Example 2)
In Example 1, the elastic roller of Comparative Example 2 was manufactured in the same manner as Example 1 except that the cutting position was changed to 0.3 mm.

(Comparative Example 3)
In Example 1, the elastic roller of Comparative Example 3 was manufactured in the same manner as in Example 1 except that the cutting position was changed to 7 mm.

(Measurement of cell diameter and hardness)
The cell diameter and hardness of the foamed elastic layer were measured by the above method. The results are shown in Table 1.

(Bubble generation)
In the elastic roller manufactured in each example, bubbles present at the end of the foamed elastic layer were confirmed as follows. That is, the diameter of the hollow region existing at the end of the foamed elastic layer was calculated by image analysis using a microscope VH-5000 (manufactured by Keyence Corporation), and the presence or absence of bubbles was determined based on the above criteria.

(durability)
The durability of each manufactured elastic roller was evaluated as follows using a durability test apparatus 70 shown in FIG.
The durability test apparatus 70 is fixed to the lower surface inside the housing, and includes a heating roller 71 provided with an internal heater 72, and a heat insulating material 73 provided on both sides of the heating roller 71 along the axial direction. A test roller mounting portion 74 provided on the upper surface inside the housing so as to be movable up and down so as to face the heating roller 71, and a pressing force adjusting means 75 capable of moving the test roller mounting portion 74 up and down, for example, pressure adjustment A micrometer. As the heating roller 71, a metal (stainless steel, SUS304) roller having a diameter of 20 mm was used.
Each elastic roller was mounted on the bearing of the test roller mounting portion 74 and the pressing force adjusting means 75 was operated to press the mounted elastic roller 76 against the heating roller 71. At this time, the elastic roller 76 was fixed at the pressure-contact portion between the heating roller 71 and the elastic roller 76 so that the foamed elastic layer of the elastic roller 76 was recessed 2 mm inside (that is, the outer diameter of the elastic roller 76 and the heating roller). The distance d between the central axis of the elastic roller 76 and the central axis of the heating roller 71 was adjusted so as to be 2 mm shorter than the sum of the outer diameters of 71 and 71).
Next, the external heater 73 and the internal heater 72 were started, and the surface temperature of the heating roller 71 was adjusted to 180 ° C. Thereafter, the driving means (not shown) provided in the test roller mounting portion 74 is continuously operated at a rotational speed of 126 rpm for 50 hours, and after the recessed state of the foamed elastic layer in the elastic roller 76 is released, the elastic roller 76 is kept at room temperature for 24 hours. Left for hours. After standing for 24 hours, after confirming the growth of bubbles at the end of the foamed elastic layer, that is, the change in the size of the bubbles, the device was continuously operated under the same conditions. During continuous operation, the growth of bubbles at the end of the foamed elastic layer was monitored every 50 hours until a total of 200 hours.
Durability was evaluated according to the following criteria by observing the end of the foamed elastic layer with a microscope in the same manner as in the above test (generation of bubbles). Even after 200 hours of operation, the case where there was no bubble growth or no bubble was evaluated as “◯” (passed). As a result of observation every 50 hours, the case where bubble growth was confirmed before operation for 200 hours was X ”(failed).

As shown in Table 1, all of the elastic rollers of Examples 1 to 6 manufactured by the method for manufacturing an elastic roller of the present invention were free from bubbles and excellent in durability.
On the other hand, in Comparative Example 1 in which a through hole was provided and in Comparative Examples 2 and 3 in which the cutting position was set to 0.3 mm or 7 mm, bubbles were generated and the durability was inferior.

DESCRIPTION OF SYMBOLS 1,76 Elastic roller 2 Shaft body 2A Cylindrical main body 2B End part 2C End surface 3 Foaming elastic layer 5 Internal space 6 Rubber composition 6a Base end side coating | coated part 6b End side coating | coated part 70 Durability test apparatus 71 Heating roller 72 Internal heater 73 Thermal insulation material 74 Test roller mounting part 75 Pressure adjusting means

Claims (7)

A method of manufacturing an elastic roller having a cylindrical main body and a shaft body having an end portion having a smaller diameter than the cylindrical main body at least at one end of the cylindrical main body, and an elastic layer on the outer periphery of the cylindrical main body,
A step of covering at least an end surface of the cylindrical main body in a sealed state with a rubber composition forming the elastic layer;
The rubber composition is sealed by removing a distal end side covering portion covering a distal end side from a proximal end covering portion covering an area of 0.5 mm or more and 5 mm or less from the end face toward the distal end of the end portion. Releasing the state and then removing the proximal covering portion;
And a step of curing the rubber composition before or after removing the base end side covering portion.   The elastic roller manufacturing method according to claim 1, wherein the covering step covers the entire shaft body.   3. The method of manufacturing an elastic roller according to claim 1, wherein in the removing step, the base end side covering portion and the tip end side covering portion are each removed once or a plurality of times.   The method of manufacturing an elastic roller according to any one of claims 1 to 3, wherein in the covering step, the rubber composition and the plurality of shaft bodies are continuously extruded.   5. The method for producing an elastic roller according to claim 1, wherein the covering step includes setting the thickness of the rubber composition covering the outer periphery of the cylindrical main body to 1 mm or more and 20 mm or less.   The method for manufacturing an elastic roller according to any one of claims 1 to 5, wherein the shaft body has an outer diameter difference between the cylindrical main body and the end portion of more than 0 mm and 15 mm or less.   The method for producing an elastic roller according to claim 1, wherein the elastic roller has an outer diameter of 20 mm to 60 mm.

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